(I) A constant friction force of 25 N acts on a 65-kg skier for 15 s on level snow.What is the skier's change in velocity?

Answer

$$
-5.8 \mathrm{m} / \mathrm{s}
$$

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Physics 101 Mechanics

Physics

Chapter 7

LINEAR MOMENTUM

Section 1

Momentum and Its Relation to Force

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Video Transcript

in this question, we asked for a change of velocity of a skier, and that skier were given that it's a skier with the sixth with sixty five kilogram mass Mass because fifty five kilograms and we have a constant friction force. Acting eyes is twenty five you Tim, and it's acting on it for a duration of fifteen seconds. So that's the trend of time. Fifty seconds. And if we first just look att What equations were learned in section one? We'LL find that too. To a queen we have first one is sea change of moment. There's more definition for mental, and from this we can also knows what gives us the change of mental. Um so if mass is constant since mo mentum question mass times velocity of masses constant, then we have a chance for mentioned because we have children velocity and another island is cockpit. Tessa's what changes momentum. So this we heard f equals Delta P over thirty somethings. A force acting over a period of time is the reasons that we have a change in momentum so we can rearrange his equation to have gotta pee, he cause you have time study so these father to creates relent, Since when? One in some point in chapter seven. And just by looking at sir, numbers were given. You can see that we already have em. We already have asked. We already have tea and we're looking for the B. So it's just talking. The numbers s obviously let's find that if on Delta P on the left hand side for both equations subversive, let us try to set his equations equal and Castle's just pee. So this gives us and time still Tuffy Eco's tens identity. I'm just trying to set this thick richest equal because the left hand side is equal to each other is because I get a piece. I'm just trying to cancel this. John is, um we can just cooking every statue. Sorry gives us We're looking for the change of velocities of this is a value what you have left unsaid. Second steers a PV because you have ten stupidity or m. So here are really tricky. Part is, we need to see that post fee and Foo Factors means they do have a direction. Ah, now we just look at it. It's a fridge in force and that means they will actually slow the skier down. Its if you are traveling in this direction. So friction forces, usually opposite direction. So this is actually negative twenty packages. So it's an active sign is here to make sure that the change in velocity of selective cause you're expected to slow down. So times fifteen seconds over mass in sixty five kilogram. And have we used all the number regular? Yes. So that's a good sign in sad kids. A selective five points seven eight Rieder procedure So that isthe Ah, change of velocity was a skier. He was slowed down by five one seven. Eight meters per second.

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